Method for recording pulmonary lesions of beef calves at slaughter, and the association of lesions with average daily gain

Abstract

A method to record lung lesions in commercial packing plants was developed as part of this observational study. Data from calves born and reared at the Roman L. Hruska U.S. Meat Animal Research Center (MARC) were used to develop the scoring method. The method was then applied to calves from three feedlots in the private sector. Lung lesion rates in MARC calves at slaughter ranged from 31 to 66% by sire line and feedlot pen. Lesions at slaughter were associated with a decrease of 0.057 lb in average daily gain (ADG). Lesions were grouped into categories: lesions that were sequela to cranial ventral bronchopneumonia (CVBP), other lesions, and no lesions. This grouping resulted in CVBP lesions being associated with a 0.073 lb reduction in daily gains, and the effect of other lesion types were not significant. Neither lobar location nor the amount of lesion present was associated with daily gains. Clinically diagnosed respiratory disease was not associated with increased frequencies of lesions at slaughter. Lung lesion rates in calves from the private sector ranged from 33 to 77% at the pen level. 30% of these calves had CVBP type lesions at slaughter that were associated with a decrease in ADG. There was a significant interaction between feedlot pen and CVBP type lesions, with an overall effect on ADG ranging from a reduction of 0.14 lb to 0.65 lb.